One of the major problems associated with the present day, known electrochemical gas sensors that utilize an aqueous electrolyte solution is the loss of water from the sensor during the sensing operations. When these prior art sensors are utilized and if the gases to be sensed are not humidified prior to applying them to the electrochemical gas sensor, the loss of water from the sensor may even be severe. The loss of water from these prior art electrochemical gas sensors can significantly affect the output signal as well as the life of the sensor. Certain types of electrochemical gas sensors can be used continuously by adding water to the sensor's body periodically, typically once a month. Some gas analyzers, such as the Teledyne Analytical Instruments Model 306WA Trace Oxygen Analyzer, have the capability to humidify the gas prior to exposure of gas to the electrochemical sensor. To utilize such equipment, however, adds substantial complications to an analysis procedure and particularly in the control of the extent to which the gases are humidified. As should be apparent, the improper control of the gas humidification of the gases undergoing sensing could either increase or decrease the water level in the sensor and, accordingly, adversely affect the output signals derived from the sensor. At the present time, therefore, there is no other known solution to the loss of water problem from an aqueous electrolyte solution.
Solid, ionic conductive elements are known and have been used in hydrogen-oxygen fuel cells, as is well-known to those skilled in the fuel cell art. The use of such solid, ionic conductive electrolyte elements in an electrochemical gas sensor, however, has not been heretofore proposed or used in such electrochemical gas sensors to solve the problems of the loss of water in the typical prior art gas sensor, as we presently understand the prior art.